The present invention relates to a stop ring, and in particular, to a stop ring for securing a valve at a predetermined position in an internal fluid passage of a hydraulic/pneumatic device member, such as a female and a male coupler constituting a pipe coupling.
FIG. 1 shows an example of a female coupler of a pipe coupling.
The female coupler 10 comprises a cylindrical female coupler body 16 including a fluid passage 14 having a male coupler inserting section 12 at one end thereof, a locking ball 18 disposed in the female coupler body for engaging with a male coupler inserted into the male coupler inserting section 12 and rigidly securing the male coupler in an inserted position, a sleeve 20 operatively mounted to an outside of the female coupler body so as to be slidable in an axial direction thereof to position the locking ball in a radial direction, and a valve assembly 22 arranged within the fluid passage 14 for opening and closing the fluid passage 14.
The valve assembly 22 comprises: a poppet valve 22-1 adapted to be movable in an axial direction of the fluid passage 14 between a closing position where the poppet valve engages with a valve seat 23 formed on a wall surface of the fluid passage to close the fluid passage, and an opening position where the poppet valve is retracted from the closing position to open the fluid passage; and a retainer 22-3 having a hole for receiving a valve stem 22-2 of the poppet valve so as to movably hold the poppet valve. The retainer 22-3 comprises a cylindrical valve retaining section 22-4 disposed in a central location of the fluid passage, and four fixing sections 22-5 extending radially outwardly from the cylindrical valve retaining section 22-4, wherein the fixing sections 22-5 engage with a stop ring 30 mounted to an interior surface of the female coupler body so as to securely hold the retainer 22-3 in the fluid passage 14.
This type of stop ring 30 is conventionally formed as a split-ring having ends (30-1 and 30-2) opposing each other in a circumferential direction. Upon fitting the ring in an annular groove 16-1 formed in the fluid passage wall, the opposing ends are pressed towards each other to reduce the diameter of the ring and thereby enable the ring to be fitted in the annular groove. Once the ring has been fitted in the groove, a contracting force to which the ring is subject before reaching the groove is released, thereby enabling the ring to expand under its own elastic force in the groove, whereby its opposing ends move apart from each other in a circumferential direction, and the ring securely seats in the groove.
The conventional stop ring described above, however, suffers from the problems detailed below.
Use of the conventional stop ring does not reliably ensure proper holding of the valve retainer. As described above, the stop ring is subject to a contracting force to reduce its diameter during fitting in the annular groove. Once the ring reaches the annular groove, it expands under its own elastic force to become securely seated in the groove, and its opposing ends move apart in a circumferential direction. Consequently, when the ring is seated in the groove a gap exists between the opposing ends 30-1 and 30-2. While the existence of such a gap enables the ring to be engaged for removal from the groove, it also gives rise to a problem that during use of the pipe coupling there is a possibility that the valve retainer 22-3 will become displaced in its circumferential direction. If such displacement occurs, one of the fixing sections 22-5 may come into mating contact with the gap between the ends of the ring, which could result in failure of the ring to hold the valve retainer 22-3.
One approach to overcoming the problem of the conventional art stated above is shown in FIG. 2. As shown in the figure, opposing and spaced apart ends 30-1 and 30-2 of the stop ring are bent to form respective radially inwardly extending protrusions. The fixing sections 22-5 are provided with notches 22-6, which are as shown in FIG. 1, formed in the radially outer edges thereof, and which are radially aligned with the setting groove 16-1 when the stop ring is installed in the valve retainer 22-3. In this way, it is possible to fit the stop ring with the notches and the protrusions 30-3 and 30-4 of the stop ring being positioned between adjacent fixing section 22-5 and 22-5 of the valve retainer 22-3. By this configuration, even if the valve retainer 22-3 is moved in the circumferential direction, one or other of the protrusions 30-3 or 30-4 will abut against one of the adjacent fixing section 22-5 and 22-5 of the valve retainer 22-3 which will prevent the fixing section from coming into mating contact with the gap between the ends 30-1 and 30-2 of the stop ring.
However, use of a process to bend each of the ends of the stop ring and/or a forming of the notches 22-6 in the valve retainer 22-3 as described above results in a significant increase in fabrication costs.
While efforts have been made in the conventional art to reduce a diameter of the stop ring for fitting in the setting groove 16-1, the work involved is complicated. In the conventional practice for reducing a diameter of the stop ring, the protrusions 30-3 and 30-4 illustrated in FIG. 2 are pulled towards each other using a tool; otherwise holes are formed in each end of the stop ring, and a tool is used to engage these holes and pull the ends of the ring towards each other. (Refer to Japanese Patent Laid-open Publication No. 2001-41332 and Japanese Patent Laid-open Publication No. Hei4-9492, the entire specifications of which are incorporated herein by reference.)
However, use of a process for forming such holes or protrusions again results in a significant increase in fabrication costs. Moreover, using a tool to engage such protrusions or holes to manipulate the stop ring is both difficult and time consuming.